Package Leaflet: Information for the User
Eutirox 25micrograms tablets
Eutirox 38micrograms tablets
Eutirox 50micrograms tablets
Eutirox 63micrograms tablets
Eutirox 75micrograms tablets
Eutirox 88micrograms tablets
Eutirox 100micrograms tablets
Eutirox 112micrograms tablets
Eutirox 125micrograms tablets
Eutirox 137micrograms tablets
Eutirox 150micrograms tablets
Eutirox 175micrograms tablets
Eutirox 200micrograms tablets
sodium levotiroxine
Read the entire package leaflet carefully before starting to take this medicine, as it contains important information for you.
Contents of the package leaflet
Levotiroxine, the active substance of Eutirox, is a synthetic thyroid hormone for the treatment of diseases and dysfunctions of the thyroid gland. It has the same effect as naturally produced thyroid hormones.
Eutirox is used
Eutirox 25 micrograms, 38 micrograms, 50 micrograms, 63 micrograms, 75 micrograms, 88 micrograms, and 100 micrograms tablets are also used to balance thyroid hormone levels when excessive hormone production is treated with antithyroid medications.
Eutirox 100 micrograms, 150 micrograms, and 200 micrograms tablets may also be used to test thyroid function.
Do not take Eutirox
in any of the following situations:
Do not take Eutirox with other antithyroid medications if you are pregnant (see the "Pregnancy and breastfeeding" section below).
Warnings and precautions
Consult your doctor or pharmacist before taking Eutirox if you have any of the following heart diseases:
These diseases must be under medical control beforeyou start taking Eutirox or before performing a thyroid suppression test. While taking Eutirox, you willneed to undergo frequent checks of your thyroid hormone levels. If you are unsure whether you have any of the described diseases or are not receiving treatment, consult your doctor.
Your doctor will investigate whether you have adrenal gland dysfunction, pituitary gland dysfunction, or uncontrolled thyroid hormone overproduction (thyroid autonomy), as this must be medically controlled before starting Eutirox or performing a thyroid suppression test.
Blood pressure should be regularly monitored when starting treatment with levotiroxine in premature infants with very low birth weight, as a rapid drop in blood pressure (known as circulatory collapse) may occur.
If you need to change your medication to another one containing levotiroxine, a thyroid imbalance may occur. Talk to your doctor if you have any doubts about changing your medication. During the transition period, close monitoring (clinical and biological) is required. You should tell your doctor if you experience any side effects, as this may indicate that your dose needs to be adjusted by increasing or decreasing it.
Consult your doctor,
Thyroid hormones should not be used for weight loss. Taking thyroid hormones will not reduce your weight if your thyroid hormone levels are within the normal range. If you increase the dose without being specifically advised by your doctor, you may experience serious side effects or even put your life at risk. High doses of thyroid hormones should not be taken with certain weight loss medications, such as amfepramone, clobenzorex, and fenilpropanolamine, as the risk of serious or life-threatening side effects may increase.
If you are going to have laboratory tests to check your thyroid hormone levels, you must inform your doctor or laboratory personnel that you are taking or have recently taken biotin (also known as vitamin H, vitamin B7, or vitamin B8). Biotin can affect laboratory test results. Depending on the test, the results may be falsely elevated or falsely reduced due to biotin. Your doctor may advise you to stop taking biotin before performing the tests. You should also be aware that other products you may be taking, such as multivitamins or supplements for hair, skin, and nails, may also contain biotin. This could affect laboratory test results. Inform your doctor or laboratory personnel if you are taking these products (see the "Other medicines and Eutirox" section).
Other medicines and Eutirox
Inform your doctor or pharmacist if you are taking, have recently taken, or may need to take any of the following medications, as Eutirox may affect their effects:
Make sure to follow the recommended time intervals if you need to take any of the following medications:
Inform your doctor or pharmacist if you are taking, have recently taken, or may need to take any of the following medications, as they may reducethe effect of Eutirox:
Inform your doctor or pharmacist if you are taking, have recently taken, or may need to take any of the following medications, as they may enhancethe effect of Eutirox:
Inform your doctor or pharmacist if you are taking, have recently taken, or may need to take any of the following medications, as they may affect the effects of Eutirox:
You may need periodic checks of your thyroid hormone levels. It may be necessary to adjust your dose of Eutirox.
Inform your doctor if you are taking amiodarone (a medication used to treat irregular heartbeats), as this medication may affect your thyroid gland function and activity.
If you need to undergo a diagnostic examination or scan with iodinated contrast media, inform your doctor that you are taking Eutirox, as you may be given an injection that can affect your thyroid function.
If you are taking or have recently taken biotin, you must inform your doctor or laboratory personnel when they are going to perform laboratory tests to check your thyroid hormone levels. Biotin can affect laboratory test results (see Warnings and precautions).
Inform your doctor or pharmacist if you are using or have recently used other medications, including those purchased without a prescription.
Taking Eutirox with food and drinks
Inform your doctor if you take products containing soy, especially if you change the amount you consume. Soy products may reduce the absorption of Eutirox from the intestine and, therefore, may require dose adjustment.
Pregnancy and breastfeeding
If you are pregnant, continue taking Eutirox. Inform your doctor, as the dose may need to be changed.
If you have taken Eutirox with an antithyroid medication to treat excessive thyroid hormone production, your doctor will advise you to stop taking Eutirox when you become pregnant.
If you are breastfeeding, continue taking Eutirox as directed by your doctor. The amount of medication excreted in breast milk is so small that it will not affect the baby.
Driving and using machines
No studies have been conducted on the effects on the ability to drive and use machinery. Since levotiroxine is identical to naturally produced thyroid hormone, it is unlikely that Eutirox will interfere with the ability to drive and use machinery.
Important information about some of the ingredients of Eutirox
This medication contains less than 23 mg of sodium (1 mmol) per tablet; it is essentially "sodium-free".
Follow exactly the administration instructions of Eutirox indicated by your doctor or pharmacist. In case of doubt, consult your doctor or pharmacist again.
Your doctor will determine your individual dose based on the exams and laboratory tests that have been performed on you. In general, it starts with a low dose that will be increased every 2 - 4 weeks, until reaching your final individual dose. During the first weeks of treatment, laboratory tests will be performed to adjust the dose.
If your baby was born with hypothyroidism, your doctor may recommend starting with a higher dose since it is important to achieve rapid replacement. The recommended initial dose is 10 to 15 micrograms per kilogram of body weight during the first 3 months. From then on, your doctor will adjust the dose individually.
In the following table, the usual dose ranges are indicated. A lower individualized dose may be sufficient,
Use of Eutirox | Recommended daily dose of Eutirox | |
| 75 – 200 micrograms | |
| 75 – 200 micrograms | |
| adults 25 – 50 micrograms* 100 – 200 micrograms | children 12.5 – 50 micrograms* 100 – 150 micrograms per m2 of body surface |
| 150 – 300 micrograms | |
| 50 – 100 micrograms | |
| If you take Eutirox 100 micrograms: 200 micrograms (2 tablets), starting 2 weeks before the test If you take Eutirox 150 micrograms: Start 4 weeks before the analysis with 75 micrograms (1/2 tablet), for 2 weeks, then 150 micrograms (1 tablet) until the analysis If you take Eutirox 200 micrograms: 200 micrograms (1 tablet), starting 2 weeks before the test |
Administration
Eutirox is used orally. Take a single dose per day on an empty stomach in the morning (at least half an hour before breakfast), preferably with a little liquid, for example with half a glass of water.
Children can take the entire daily dose of Eutirox at least half an hour before the first meal of the day. Immediately before taking, crush the tablet and mix it with a little water and give it to the child with some more liquid. Always prepare the mixture at the time of taking it.
Duration of treatment
The duration of treatment may vary depending on the indication for which you use Eutirox. Therefore, your doctor will inform you about the duration of treatment. Most patients have to take Eutirox for the rest of their lives.
If you take more Eutirox than you should
If you have taken a dose higher than prescribed, you may experience symptoms such as rapid heartbeats, anxiety, agitation, or involuntary movements. In patients with neurological disorders such as epilepsy, seizures may occur in isolated cases. In patients at risk of psychotic disorders, symptoms of acute psychosis may occur. If this happens to you, consult your doctor.
In case of overdose or accidental ingestion, consult the Toxicological Information Service: Phone: 915 620 420.
If you forgot to take Eutirox
Do not take a double dose to make up for forgotten doses, take the normal dose the next day.
If you have any other doubts about the use of this product, ask your doctor or pharmacist.
Like all medications, Eutirox can produce adverse effects, although not all people suffer from them.
You may experience one or more of the following adverse effects if you take more Eutirox than indicated or if you do not tolerate the prescribed dose (for example, when the dose is increased rapidly): irregular or rapid heartbeats, chest pain, headache, muscle weakness or cramps, flushing (heat and redness of the face), fever, vomiting, menstrual changes, pseudotumor cerebri (increased cranial pressure), tremors, agitation, sleep changes, sweating, weight loss, and diarrhea.
Consult your doctor if you observe any of these effects. Your doctor may consider interrupting treatment for several days or reducing the daily dose until the adverse effects have disappeared.
It is possible that you may suffer an allergic reaction to any of the components of Eutirox (see section 6 "Composition of Eutirox"). Allergic reactions can include rash, hives, and swelling of the face or throat (angioedema). If this happens, consult your doctor immediately.
If you consider that any of the adverse effects you suffer from is serious or if you notice any adverse effect not mentioned in this prospectus, inform your doctor or pharmacist.
Reporting of adverse effects
If you experience any type of adverse effect, consult your doctor or pharmacist, even if it is a possible adverse effect that is not mentioned in this prospectus. You can also report them directly through the Spanish Pharmacovigilance System for Human Use Medicines: www.notificaRAM.es.
By reporting adverse effects, you can contribute to providing more information on the safety of this medication.
Keep this medication out of sight and reach of children.
Do not use Eutirox after the expiration date that appears on the packaging, after CAD. The expiration date is the last day of the month indicated.
Do not store at a temperature above 25 °C. Keep in the original packaging to protect it from light.
Medications should not be thrown down the drain or into the trash. Deposit the packaging and medications you no longer need at the SIGRE Point in the pharmacy. In case of doubt, ask your pharmacist how to dispose of the packaging and medications you no longer need. This way, you will help protect the environment.
Composition of Eutirox
The active principle is levothyroxine.
Each Eutirox 25 microgram tablet contains 25 micrograms of sodium levothyroxine.
Each Eutirox 38 microgram tablet contains 38 micrograms of sodium levothyroxine.
Each Eutirox 50 microgram tablet contains 50 micrograms of sodium levothyroxine.
Each Eutirox 63 microgram tablet contains 63 micrograms of sodium levothyroxine.
Each Eutirox 75 microgram tablet contains 75 micrograms of sodium levothyroxine.
Each Eutirox 88 microgram tablet contains 88 micrograms of sodium levothyroxine.
Each Eutirox 100 microgram tablet contains 100 micrograms of sodium levothyroxine.
Each Eutirox 112 microgram tablet contains 112 micrograms of sodium levothyroxine.
Each Eutirox 125 microgram tablet contains 125 micrograms of sodium levothyroxine.
Each Eutirox 137 microgram tablet contains 137 micrograms of sodium levothyroxine.
Each Eutirox 150 microgram tablet contains 150 micrograms of sodium levothyroxine.
Each Eutirox 175 microgram tablet contains 175 micrograms of sodium levothyroxine.
Each Eutirox 200 microgram tablet contains 200 micrograms of sodium levothyroxine.
The other components are cornstarch, citric acid, sodium croscarmellose, gelatin, magnesium stearate, and mannitol (E 421).
Appearance of the product and content of the packaging
Eutirox tablets are white, round, flat on both sides, beveled, with a partition groove, and with the inscription "EM 25", "EM 38", "EM 50", "EM 63", "EM 75", "EM 88", "EM 100", "EM 112", "EM 125", "EM 137", "EM 150", "EM 175", or "EM 200" on one side.
Eutirox is available in packages of 20, 25, 30, 50, 60, 90, 100, or 500 tablets, or in calendar packages of 28 or 84 tablets.
Only some package sizes may be marketed.
Marketing authorization holder and manufacturer
Marketing authorization holder
Merck, S.L.
María de Molina, 40
28006, Madrid, Spain
Manufacturer
Merck Healthcare KGaA
Frankfurter Strasse 250
64293 Darmstadt, Germany
FAMAR HEALTH CARE SERVICES MADRID, S.A.U.
Avda. Leganés, 62
Alcorcón, 28923 Madrid, Spain
This medication is authorized in the Member States of the European Economic Area with the following names:
Austria: Euthyrox
Denmark: Euthyrox
Germany: Euthyrox
Greece: Euthyrox
Iceland: Euthyrox
Croatia: Euthyrox
Norway: Euthyrox
Portugal: Eutirox
Spain: Eutirox
Sweden: Euthyrox
Date of the last revision of this prospectus:07/2024
Other sources of information
You can access detailed and updated information about this medication by scanning the QR code included in the packaging with your mobile phone (smartphone). You can also access this information at the following internet address:
Eutirox 25 micrograms: https://cima.aemps.es/info/64011
Eutirox 38 micrograms: https://cima.aemps.es/info/89799
Eutirox 50 micrograms: https://cima.aemps.es/info/64012
Eutirox 63 micrograms: https://cima.aemps.es/info/89800
Eutirox 75 micrograms: https://cima.aemps.es/info/64013
Eutirox 88 micrograms: https://cima.aemps.es/info/70044
Eutirox 100 micrograms: https://cima.aemps.es/info/64014
Eutirox 112 micrograms: https://cima.aemps.es/info/70042
Eutirox 125 micrograms: https://cima.aemps.es/info/64015
Eutirox 137 micrograms: https://cima.aemps.es/info/70043
Eutirox 150 micrograms: https://cima.aemps.es/info/64016
Eutirox 175 micrograms: https://cima.aemps.es/info/64017
Eutirox 200 micrograms: https://cima.aemps.es/info/64018
and on the website of the Spanish Agency for Medicines and Health Products (AEMPS) http://www.aemps.gob.es/.
The average price of EUTIROX 112 micrograms TABLETS in October, 2025 is around 5.18 EUR. Prices may vary depending on the region, pharmacy, and whether a prescription is required. Always check with a local pharmacy or online source for the most accurate information.